Hierarchical NiSx/Ni2P nanotube arrays with abundant interfaces for efficient electrocatalytic oxidation of 5-hydroxymethylfurfural

Abstract

Electrochemical oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA) has drawn wide attention recently. Rational interface engineering can modulate the electronic structure, tune the adsorption energy and endow the hybrid material with more active sites for HMF electrochemical oxidation. Herein, we propose a strategy for the synthesis of metal sulfide/metal phosphide (MS_x/MP_y, M = Co, Fe, Ni…) nanotube arrays with abundant interfaces by the sequential electrodeposition interface engineering method. Since Ni-based electrocatalysts show high efficiency for the electrochemical oxidation of HMF, we designed and synthesized interface-rich heterogeneous NiS_x/Ni₂P nanotube arrays. The abundant interfaces promote electron transfer between NiS_x and Ni₂P, which synergistically improves the oxidation state of the Ni species and further enhances the electrocatalytic performance of HMF oxidation. The NiS_x/Ni₂P electrocatalyst shows superb HMF oxidation activities with a low onset potential of 1.25 V vs. RHE. A current density of 20 mA cm⁻² can be reached at 1.346 V vs. RHE, which is reduced by 204 mV compared with that with water oxidation. Chronoamperometry electrolysis reveals that HMF conversion is nearly 100% and FDCA selectivity can reach 98.5%.